Heating apparatus



July 2, 1946-` H. J. N. MccovLLUM l I 2,403,188

HEATING APPARATUS Filed June 17, .1942, 5 Sheets-Sheet 1 Q v v9 I. 3 91N QQ Q u@ g N) lJuly 2 1946- H. l.L DE N. MccoLLUM A 2,403,188

HEATING APPARATUS Filed June 17, 1942 :s sheets-sheet 2 July 2, 194s. H.4; DE N. MCCLLUM y A2,403,138

HEATING APPBATUSl Filed June 1'7, 1942 3 Sheets-Sheet 3 Patented July 2,1946 HEATmG APPARATUS Henry' .L DeN. McCollum,"y chicago, nl.; ThelmaMcCollum, executrix of said Henry, J. DeN.

McCollum, deceased Application June 17, 1942, Serial No. 447,345'

. 2 Claims.

1 n; My invention relates generally to internal 'combustiontype'heaters, that is, heaters in which combustion takes place in a.sealed combustion chamber, and more particularly to heaters of this typefor use on aircraft and other vehicles in which maximum heat productionis desired from a heater oi minimum size and weight.

It is an object of my invention to provide an improved heater of theinternal combustion type incorporating means to secure uniform andnonexplosive combustion of a combustible mixture of fuel (such asgasoline) and air.

A further object is to provide an improved internal combustion typeheater `which is constructed to prevent explosive combustion in theevent that the flame in the heater should become accidentallyextinguished.

A further object is to provide an improved internal combustion typeheater having means to prevent hash-back of the flame into the conduitthrough which the combustible mixture is supplied to the heater.v

A further object is to provide an improved interna1 combustion typeheater which is quiet in operation.

A further object is to lprovide an improved internal combustion typeheater which'can be economically constructed, which will be highlyefflcient, which will operate satisfactorily under varying conditions,and which will have a long useful life. f l y l Other objects willappear from the following description, reference being had to theaccompanying drawings, in which:

Fig. 1 is a fragmentary sectional view ofthe heater, the sections beingtaken along a `central longitudinal plane;

Fig. 2 is a, fragmentary sectional view taken yon the line 2-2 of Fig.1;

Fig. 3 is an end elevational view taken on the line 3-3 of Fig. 1, aportion of thecasing being broken away to show the igniter;

Fig. 4 is an end elevational view taken on the line 4-4 of Fig. 1;

Fig. 5 is a fragmentary sectional view to a larger scale than Fig. 1,showing particularly the shield for the igniter;

Fig. 6 is a, fragmentary sectional View taken on the line 6-6 of Fig. 5;

Fig. 7 is a fragmentary transverse sectional view taken on the line 1-1of Fig. 1; and,

Fig. 8 is a wiring diagram of the electrical components of the heater.

Heaters of the type to which my invention appe'rtains are supplied witha combustible mixture to control the rate of flow of thecombustiblemixture to the heater.

Within the outlet portion of the fitting I0 is a flame arrester I8,which, as best shown in Fig. 2, comprises a plurality of small diametertubes 20, which may be made of copper or other good conducting metal.'I'he overall cross-sectional areas. of the bores through the tubes 20,plus the cross-sectional area of the spaces between thesetubes, issuiiiclently large so that the iiame arrester does not oiier anundesirably high resistance tovlow of the combustible mixture throughthe llame arrester. The tubes, however, are of such small diameter thatthey may act in a well known manner to prevent the propagation `of aflame through the flame arrester.

The valve fitting I0 is suitably secured to the inlet boss 22 of acombustion chamber casting 24 by studs 26, a portion of the wall of amain casing 28 being clamped between the fitting I0 and the boss 22.It'will be noted that the llame arrester tubes 20 are located in acylindrical tube 30, which extends into the bore of the boss 22 and hasa reduced diameter end portion 32,

which projects into a combustion chamber 34 formed within the casting24. The portion 32 is provided with a plurality of ports 36 formed bylouvers 38 struck inwardly from the portion 32 to cause the combustiblemixture to i'low in a circular path as it leaves the ports 36. A ring 40is located within the tube 30 to form a smooth velocity of ow increasingthroat, while a cusp'- shaped plug 42 is secured within the end of theprojecting portion 32. By virtue of the provision of the ring 40 andp1ug'42, as well as the louvers 33,` the mixture enters the combustionchamber with a smooth uniform vertical iiow.

As best shown in Figs. 5 'and 6, thecombustion chamber casting 24 isprovided with a sidewardly extending boss 46, which is threaded toreceive an igniter plug 48, within .which is locateda coiled wire 50 ofNichrome orsimilar high resistance metal.. the inner end of this coilbeing welded tothe inner end ofthe plug-48 and the ture in thecombustion chamberfrom too rapidly 5 cooling the igniter coil 50 whenthe latter is energized, the casting 24 isformed to provide a baffle 54.This, baii'e is generally convex in shape to provide openings at its topand bottom for the circulation of the combustible mixture past the' l0hend of the igniter coil 50. By thus restricting the` circulation of thecombustible mixturepastthegigniter wire coil, the latter may be heatedmore ra'pidly to a temperature at which? it Vw'ill "ign'ntep 5 themixture, and, since thefrnxtureY vflows* `past '15'5 the igniter at alower velocity, it is more susceptible to ignition. The ignition l'ofthe-mixture is thus greatly facilitated by theV provision of the.-

baille 54. This is an important factor in securving reliable ignition ofYthe mixture at extremely low'A temperatures and when'themixtureis'supplied at lless than atmospheric pressures, aswhen theheater is; used upon aircraft flying atlhigh altitudes. f

In order to make it unnecessary-to reenergize the igniter 50 wheneverthe flame in the'combustion chamber is vaccidentally extinigulshed V dueto a temporary; interruption in the supply ofV combustible mixture, or atemporary change inthe proportion of fuel to air in the mixture whichmay render the mixture vcomparatively incombu'stible; there is providedAareigniter 56;. which is secured to a plug 58 andi extends horizontallyinto the combustion chamber. This regniter is preferably in' the form of'a spirally coiled sheet or Inconel or similar heat. and corrosion`resistant metal. '5

i The combustion chamber casting 24 is secured to a clamping ring 59 bya plurality of'stucls 60,

the ring v59 having a. plurality of Yradially extendf ing Yarms 62, towhich the outer casing 28 is fixed by"screws 54. A heat exchangershell166, preferably made of copper or other good heat conductor,Vhasits flanged end 63 clamped be:- twe'en the ring' 58 and the casting24, a suitable gasket lbeing provided to seal this joint. The other endof theshell. 0E is brazed'or otherwise suitably secured Vto an outletfitting l2.A

` Within the shellVV 68 is a hollow filter land muffierV structurecomprising aV cylindricaltube" i4 having aV plurality of radial ribs16;' 'Y The outer end surfaces'cf the ribsl are'of the same diam'- eteras the inside diameterV of the shell Slgso that there is a press-fitcontact between the' ends of the ribs andthe shell 66, resulting in goodheat conductionjbetween these parts; `The cylindricalft'ube 14 has apluralityof spacedsmall diameter ports, i8 formed' thereirr.at'fthe:bases of thegrooves between the rlbsI-'lftov provide Vre.-

strictedcommunication I with the. interior' of: the f tube 14. The tubeI4 isfllled? with7 a Asuitable sound and vibrationdamping material',such as stainless steel wool or glassxwool $30'. The.' 'conr- Y bustionchamber endjof the-'cylinder 14 is' closed byY a plug V82, while thedischarge rend. orthis f cylinder vis closed by a hollowgenerallyfconical endl cap 84, which issuitably flanged toipermit theadjacent. end ofthe cylinder. 14' to; besecurled theretobyaspinning.operation.:AV f'. fY

`A bolt 88 isjriveted-inzthe end* cap 84 Yanizljprn- Y jects through `asuitable boss/8.8 Vformed'ontlfie outletftting '|2; ajnut fbeingthreaded? on; this bolt 'to make it possiblev to dra'w the .en-d* cap?84 and. parts,V assembled fftherewithinto. properly spaced: relationshipgiwitrrres-pecttogthe outlet 'fitshaped portion projecting into the bore86. The outerend of the nozzle 98 is suitably threaded for' connectionto a discharge cond-uit.

The combu'stionichamber casting 24 is providedfwjthaplurality of heatradiating lns |00, whilefthe shell Bfls provided with a plurality of4genera-llyradial fins |02, which may be brazed or, ldepending upon themetals used, welded to the shell. Ihese ns |02 preferably extend intoclose proximity with the inner surface of the outercasing-'28L The outercasing 28- is secured to'the heat yexchange' assembly notl only byf thenozz-le'ttingd, VA suitablyanged bracket |04 issecuredtortheoutletgi'itting '|12 and to the outer casing 28 (see Fig.4) The outer casing 28v has'a flange |06 at its vinlet end for/attachment toV a blower or aconduitl through which airtofbe heated isconveyed, and has asimilar flange |01 at itsV outlet end Vfor connectionwith aconduit for conveying theA heated airv tothe space tobe heated.:The casing 28 also has a projecting portion |08 (Fig. 3) -suitablytoprotect the igniter plug 48 and theelectrica-l connectionsthereto andalso isprovided witha protuberance ||0 tojhouse anc electricalconnection fitting.

The temperature; responsive overheat switch |24 (Fig. 8) is mountedfinav tuba 2^-(Flg.i 3)., which isV located betweenffins |02 near theV,corn- Vbust-ion chamber. f A temperatureresponsive: lg'- rlter switch|22 (Fig. 85) may be located-in a tube I4Y (Figg'l) inear the outlet endof the 4heat` grounded. Uponclosing `a'niaster control switch` |20,current ls. supplied through a thermostatically operated igniter switch|22 (in tube ||4) toi'gnit'e'rf 50, the other terminal of whichl isconnected toground;v Thermostatic switchesv |24 and |25 are connected'vinY series with a solenoid operated valve'l2'8 by which the '.supplyioffuel mixture to the heater isjcontrolled. The switches |24 and |25 arecontained intubesv IfIZand'fiII-B,

respectively.v l

It will be apparentfthatxupon. closure tof".` the switch|'20-...the-igniterll=will bey energized', and,

Vassurningfthat the heateriis cold,.the switches; |24

and las will `iiecioseu :anuthe solenoid 'vais/e428 thus" energized.Thus, -thev supplyiof fuel mixture is fed to the heater and ignitedfby'the l'iotz're-l-V Y sistancev wire igniter 50. lAsv soon as,c the heaterhas'attained substantially its normal. 'operating' temperature, thethermostatic. switch: L22.-V will open' to cut 'off -thefcurrentisupplyto tha-igniter.

If for any reason the heaterj shouldbecomeex- `cessively hot,.ras1byfailure'ofgthe, supply; ofivntilating airji forced: thrdughlthejcasingijfthe high temperature as td :cause :ittdop'err` thehincuit; to.. the.- .solenoid valve .i |28, :whereupon: the

terrupted, and dangerous overheating of the apparatus prevented. v

In normal operation, the air flow through the flame arrester I8 issuiliciently rapid and these tubes are of sufficiently small diameterthat the flame from the combustion chamber cannot flash back throughthese tubes and the spaces between them to the inlet iitting l0. Themixture sup'- plied through the flame arrester I8 is maintained at highvelocity due to the constriction formed by the member 40, and themixture is given a rotary component of flow by the louvre vanes adjacentthe ports 36. This rotary iiow results in complete mixing of the fueland air, so that it will be substantially uniform as it meets theburning mixture in the combustion chamber. pronounced turbulence doesnot, however, interfere with initial ignition of the mixture by theigniter 50 because of the protecting baflle54, which shields the igniterfrom this rapid ilow.

Due to the fact that the combustion chamber is L-shaped, the degree ofturbulence is increased so that complete combustion takes place andthere is no possibility of a stream of fuel mixture passing through thecombustion chamber Without burning. This is an important factor when theheater is used on aircraft ilying at high altitudes. Under thesecircumstances, the air of the mixture is so rareied that all conditionsmust be favorable in order that combustion may be maintained within thecombustion chamber. 'I'he difficulty of thisV problem may be appreciatedby the fact that a candle will not burn when This in atmosphere at apressure corresponding to that mixture, is inhibited by the provision ofthe muff ing or sound vibration filtering chamber 2|), whichcommunicates with these passageways through the small holes '18.V Thismuiller construction is of importance in assuring steady and uniformcombustion under varying conditions of operation.

The combustible mixture leaving the passageways between the ribs 16flows through the restricted passageway 94 at a relatively high velocvity. It is of importance to Vreduce the volume of this passageway 12 toa minimum in order to prevent, immediately after starting operation ofthe heater, an accumulation of gas mixture which might be ignited by theheated products of combustion and cause an explosion. Such explosive l 6,f Y combustion in this passageway might cause extinguishment of theiiame in the combustion chamber due to the interruption of the supplyY`to a space of lower pressure than that of the fuel mixture supply. TheVenturi-shaped passageway in the outlet fitting 98 has the advantageousproperty of appreciably compensating for changes in relative pressure ofthe fuel mixturesupply and exhaust and functions in a manner more fullydisclosed 'in my prior Patent No.

aierglvsa f While I have shown and described a particular embodiment ofmy invention, it will be ap parent to those skilled in the art thatnumerous modifications and variations may be made without departing fromthe underlying principles `of. the invention. I therefore desire, by thefollowing claims,v to include within the scope of the invention all suchmodifications and variations by whichsubstantially the results thereofmay be obtained by the use of substantially the same or equivalentmeans.

I claim:

1. In a heater of the internal combustion type, a combustion chambercasting having an elbowshaped combustion chamber formed therein, anigniter receiving opening extending into said combustion chamber, anigniter element secured to said casting and communicating with saidcombustion chamber'through said opening, a connection to one end of saidcombustion chamber for supplying a combustible mixture theretoa heatexchanger, a connection securing said heat exchanger to the other end ofsaid combustion chamber casting-and a reigniter elementextending intosaid combustion chamber in a direction toward said heat exchanger andremovable therefrom without disturbing the other connectionsv to saidcombustion chamber casting.

2. In a heaterA of the internal combustion type having means forsupplying a fuel mixture and means for withdrawing the products ofcombustion therefrom, the combination of a casting A having an L-shapedcombustion chamber formed therein and said casting forming a smallerspace Y communicating with the combustion chamber, an electrical ignitersecured to said casting and having its igniting element located in saidspace, and Y a baille forming part of said combustion chamber castingand located in front of said space to prevent direct iow of combustiblemixture from said combustion chamber to the igniter element.

HENRY J. DEN. McCOLLUM.

